This is an aneurysm of the right anterior cerebral artery (MCA). In October 1998 the aneurysm was successfully coiledb y percutaneous transluminal embolization with GDC coils (platinum spiral) after a subarachnoid hemorrhage Hunt & Hess I°.
In 03/2004 (5 1/2 years after embolization), the aneurysm became symptomatic, the patient developed epilepsy. Because of an increase in size and re-established blood circluation (prone to rupture and bleeding) the aneurysm was clipped and surgically removed.
You can see the different signal intensities within the aneurysm and the onion-like structure. The onion like structure is caused by alternating reperfusion and thrombosis of the aneurysm.
